Lichen

:For other things named "lichen", see: Lichen (disambiguation).

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Lichens are symbiotic organisms made up by the association of microscopic green algae or cyanobacteria and filamentous fungi. Lichens take the external shape of the fungal partner and hence are named based on the fungus. The fungus most commonly forms the majority of the lichen's bulk, though in filamentous and gelatinous lichens this may not always be the case. The lichen fungus is typically a member of the Ascomycota—rarely a member of the Basidiomycota. Some lichen taxonomists place lichens in their own division, the Mycophycophyta, but this practice ignores the fact that the components belong to separate lineages.

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The algal cells contain chlorophyll, permitting them to live in a purely mineral environment by producing their own organic compounds (see photosynthesis). The fungus protects the alga against drying out and, in some cases, provides it with minerals obtained from the substratum. If a cyanobacterium, such as in Terricolous Lichens, is present this can fix atmospheric nitrogen, complementing the activities of the green alga.

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Symbiotic: REDIRECT Symbiosis...

Green alga: Chlorophyta Charophyta Streptophytina (Subdivision)The green algae are the large group of algae from which the embryophytes (higher plants) emerged. As such they form a paraphyletic group, variously included among the Plantae or with the Protista. The green algae include unicellular and colonial ...

Cyanobacteria: The taxonomy of the Cyanobacteria is currently under revision. see http://ijs.sgmjournals.org/cgi/content/abstract/54/5/1895...

Lichen related Images and Photos (experimental)

Beard Lichen (Usnea Strigosa) Growing on a Oak Tree Limb Florida USA

Close-Up of Map Lichen and Moss